Schema does not change automatically. We generally add new columns to the subscriber before adding them to the publisher if we want zero impact. But if we don't

Schema does not change automatically. We generally add new columns to the subscriber before adding them to the publisher if we want zero impact. But if we don't, there's no data loss we just end up with replication held up until the column is added. Stored procedures, triggers, etc. don't exist on the subscriber. They just get any mutations on any tables they are subscribed to.